Wireless Sensor Network with Mesh Topology for Carbon Dioxide Monitoring in a Winery

During fermentation of juice to wine, the conversion of sugar to alcohol produces carbon dioxide (CO2). For a single liter of juice that is fermented, approximately 64 liters of pure CO2 is produced. The OSHA permissible exposure limit of CO2 is 5000 ppm for 8 hours of exposure, approximately 10 times the CO2 content of the atmosphere. It would take 200 liters of fresh air to dilute a single liter of pure CO2 to permissible level. Considering a typical fermentation tank can hold approximately 5000 liters of juice and a winery will ferment in many tanks at the same time, the levels of CO2 produced poses a significant safety hazard and must be controlled. Since CO2 is denser than air, a vertical separation will exist, in addition to the inherent variability in CO2 emission and distribution across a floor plan. Existing CO2 monitoring devices for wineries typically consist of a single sensor mounted on the wall, providing only a point measurement, however, the spatial dependency of CO2 lends itself to a multi-sensor system. A wireless sensor network system for CO2 and environmental monitoring in a winery and creamery was shown by Madrid et al. 2017 [1]. This work demonstrated the need for a multi-point sensor network by showing that a sensor network recorded CO2 levels near the permissible exposure limit of 5000 ppm, despite an existing CO2 point measurement system that controls exhaust fans in a winery fermentation room. The system utilized IEEE 802.15.4 communication protocol over 2.4 GHz to form a star network, however, multiple star networks were needed to provide coverage for a large facility with many RF obstructions. In some cases, a Yagi directional antenna was used on the central node to reach edge nodes far away. Our work addresses the problem of RF connectivity by implementing a mesh network, allowing data to be routed through multiple pathways between nodes.